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LibWeb+LibWasm: Implement and use the "reset the Memory buffer" steps

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This implements the memory object cache and its "reset on grow"
semantics, as the web depends on the exact behaviour.
This commit is contained in:
Ali Mohammad Pur 2023-03-29 01:31:51 +03:30 committed by Andreas Kling
parent 14fb6372c3
commit 64da05a96d
Notes: sideshowbarker 2024-07-17 07:08:37 +09:00 
Author: https://github.com/alimpfard
Commit: https://github.com/SerenityOS/serenity/commit/64da05a96d
Pull-request: https://github.com/SerenityOS/serenity/pull/18079
3 changed files with 55 additions and 5 deletions
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15
Userland/Libraries/LibWasm/AbstractMachine/AbstractMachine.h
View file

@ -398,7 +398,12 @@ public:
auto& data() const { return m_data; }
auto& data() { return m_data; }
bool grow(size_t size_to_grow)
enum class InhibitGrowCallback {
No,
Yes,
};
bool grow(size_t size_to_grow, InhibitGrowCallback inhibit_callback = InhibitGrowCallback::No)
{
if (size_to_grow == 0)
return true;
@ -416,9 +421,17 @@ public:
m_size = new_size;
// The spec requires that we zero out everything on grow
__builtin_memset(m_data.offset_pointer(previous_size), 0, size_to_grow);
// NOTE: This exists because wasm-js-api wants to execute code after a successful grow,
// See [this issue](https://github.com/WebAssembly/spec/issues/1635) for more details.
if (inhibit_callback == InhibitGrowCallback::No && successful_grow_hook)
successful_grow_hook();
return true;
}
Function<void()> successful_grow_hook;
private:
explicit MemoryInstance(MemoryType const& type)
: m_type(type)

41
Userland/Libraries/LibWeb/WebAssembly/Memory.cpp
View file

@ -25,7 +25,12 @@ WebIDL::ExceptionOr<JS::NonnullGCPtr<Memory>> Memory::construct_impl(JS::Realm&
if (!address.has_value())
return vm.throw_completion<JS::TypeError>("Wasm Memory allocation failed"sv);
return MUST_OR_THROW_OOM(vm.heap().allocate<Memory>(realm, realm, *address));
auto memory_object = MUST_OR_THROW_OOM(vm.heap().allocate<Memory>(realm, realm, *address));
Detail::s_abstract_machine.store().get(*address)->successful_grow_hook = [memory_object] {
MUST(memory_object->reset_the_memory_buffer());
};
return memory_object;
}
Memory::Memory(JS::Realm& realm, Wasm::MemoryAddress address)
@ -52,26 +57,54 @@ WebIDL::ExceptionOr<u32> Memory::grow(u32 delta)
return vm.throw_completion<JS::RangeError>("Could not find the memory instance to grow"sv);
auto previous_size = memory->size() / Wasm::Constants::page_size;
if (!memory->grow(delta * Wasm::Constants::page_size))
if (!memory->grow(delta * Wasm::Constants::page_size, Wasm::MemoryInstance::InhibitGrowCallback::Yes))
return vm.throw_completion<JS::RangeError>("Memory.grow() grows past the stated limit of the memory instance"sv);
TRY(reset_the_memory_buffer());
return previous_size;
}
// https://webassembly.github.io/spec/js-api/#reset-the-memory-buffer
WebIDL::ExceptionOr<void> Memory::reset_the_memory_buffer()
{
if (!m_buffer)
return {};
auto& vm = this->vm();
auto& realm = *vm.current_realm();
MUST(JS::detach_array_buffer(vm, *m_buffer, MUST_OR_THROW_OOM(JS::PrimitiveString::create(vm, "WebAssembly.Memory"sv))));
auto buffer = TRY(create_a_memory_buffer(vm, realm, m_address));
m_buffer = buffer;
return {};
}
// https://webassembly.github.io/spec/js-api/#dom-memory-buffer
WebIDL::ExceptionOr<JS::NonnullGCPtr<JS::ArrayBuffer>> Memory::buffer() const
{
auto& vm = this->vm();
auto& realm = *vm.current_realm();
auto* memory = Detail::s_abstract_machine.store().get(address());
if (!m_buffer)
m_buffer = TRY(create_a_memory_buffer(vm, realm, m_address));
return JS::NonnullGCPtr(*m_buffer);
}
// https://webassembly.github.io/spec/js-api/#create-a-memory-buffer
WebIDL::ExceptionOr<JS::NonnullGCPtr<JS::ArrayBuffer>> Memory::create_a_memory_buffer(JS::VM& vm, JS::Realm& realm, Wasm::MemoryAddress address)
{
auto* memory = Detail::s_abstract_machine.store().get(address);
if (!memory)
return vm.throw_completion<JS::RangeError>("Could not find the memory instance"sv);
auto array_buffer = JS::ArrayBuffer::create(realm, &memory->data());
array_buffer->set_detach_key(MUST_OR_THROW_OOM(JS::PrimitiveString::create(vm, "WebAssembly.Memory"sv)));
return array_buffer;
return JS::NonnullGCPtr(*array_buffer);
}
}

4
Userland/Libraries/LibWeb/WebAssembly/Memory.h
View file

@ -38,7 +38,11 @@ private:
virtual JS::ThrowCompletionOr<void> initialize(JS::Realm&) override;
WebIDL::ExceptionOr<void> reset_the_memory_buffer();
static WebIDL::ExceptionOr<JS::NonnullGCPtr<JS::ArrayBuffer>> create_a_memory_buffer(JS::VM&, JS::Realm&, Wasm::MemoryAddress);
Wasm::MemoryAddress m_address;
mutable JS::GCPtr<JS::ArrayBuffer> m_buffer;
};
}